1. Field of the Invention
This invention relates generally to freight vehicles and more particularly to freight vehicles having a cargo space which is convertible between handling piece goods and handling bulk goods, such as granular, powder, flake or fluid material.
2. Prior Art
Freight vehicles which can handle either piece goods or bulk goods are generally known. The advantage of such convertibility is that the same cargo space on the same vehicle could handle either of these two significantly different types of loads. The term "piece goods" is defined herein to mean any goods which are handled as individual items or pieces, including packaged goods or palletized goods. The term "bulk goods" means any goods which are pourable and commonly shipped in bulk, such as powder, grain, flake or fluid materials. The term "freight vehicle" encompasses any vehicle capable of containing freight or cargo, including without limitation tractor-trailers, railway cars, ships, and aircraft.
For example, U.S. Pat. No. 4,534,596, issued Aug. 13, 1985, incorporated in its entirety by reference herein, discloses a freight vehicle having a conventional cargo space for piece goods, wherein the cargo space includes openings in the roof and floor for filling and discharging bulk material. Specially constructed bulk material container bags are deployed from the roof under the inlet openings and extend to the floor over the outlet openings. The bags are filled with bulk material through the inlet openings in the roof, and when the vehicle has arrived at the shipment destination the material is discharged from the outlet openings in the floor. To allow handling of piece goods, the bags are retractable to a stored and locked position on the ceiling of the cargo space.
FIGS. 1-5 illustrate the details of the prior art freight vehicle with convertible cargo space as discussed above. FIG. 1 shows a side view and FIG. 2 shows a top view of the vehicle. As shown in FIGS. 1 and 2, a freight vehicle in the form of a semi-trailer 12 has wheels 14 for transport over a roadway R and a ground support member 16. Trailer 12 has a floor 18, side walls 20 and 22, a front-end wall 24, a rear-end wall 28, and a roof 26. Rear-end wall 28 may contain access doors 25.
A plurality of bulk cargo bags 30 are provided in the trailer 12 for the storage and transportation of bulk goods. Each pair of bags is positioned on a rigid bottom support platform 32. The bags 30 each include a fill cap arrangement 96 located in the inlet opening in the roof 26 of the trailer (and also corresponding discharge cap arrangements located in the floor openings, not shown). Bags 30 can be any suitable type of foldable or retractable bulk cargo container, and are preferably double wall inflatable bags which discharge their loads first by gravity and then by pneumatically assisted gravity discharge. The bags are inflated by conventional blowers 34. See U.S. Pat. No. 4,421,250 for a detailed disclosure of the bags 30.
A plurality of cables 38 extend upward from each platform 32 to the top of the cargo space and then across to a pulley box 40. A winch 36 is provided for winding and unwinding the cables 38 to raise and lower the platforms 32 between the roof and floor of the trailer, and thus deploy and retract the bags 30. Platform guide posts 42 are positioned against the side walls of the trailer and provide vertical guide channels as shown in FIG. 3. A center post 52 is provided against one side wall to provide support for the winch 36 via a cross beam 51. T-shaped guide members 54 extend from each platform 32 and ride within the vertical channels of the guide posts 42 to guide the platforms as they are raised via cables 38. Vertical beams 50 may be provided to compartmentalize pallets P which may be stored in the center of the trailer between two bags. As shown in FIG. 4, each cable 38 is connected to the platform via a connection such as turnbuckle 56 and extends upwardly over a pulley 58 held by a pulley bracket 60, to the pulley box 40. As shown in FIGS. 3 and 5, an angle member 68 is provided between adjacent bags and attached to bag retainer rings 86. Additional T-shaped guide members 66 extend from members 68 and have their heads within vertical channels of guide post members 44. An adjustable stop 70 is provided to limit the downward extension of the guide rings 86.
In operation, when it is necessary to transport bulk material, the winch 36 is activated to deploy the bags 30 through the unwinding of the cables 38. The bags are filled with the bulk material, and are emptied at the destination location. At that time, the winch 36 is activated to retract the bags for stowage adjacent the roof, in order that piece goods may then be loaded into the trailer.
A shortcoming in the above-described prior art convertible freight vehicle is the relative complexity of the deployment system for the bulk cargo bags. Although any conventional cargo vehicle may be converted to a convertible piece/bulk goods vehicle by simply providing openings in the roof and floor of the vehicle, the installation of the prior art retractable cargo bag system is expensive and time-consuming. This is caused by the combination of the winch 36 and cables 38 which are carried to the winch via a complex system of pulleys and associated support and housing members, which must be installed in the trailer, and the fact that a plurality of guide posts and support posts also must be installed on the side walls of late model thin-walled trailers, to provide the support for the winch and the guide channels for the bottom support platforms.
Additionally, repeated raising and lowering operations subject the cables and pulleys to excessive wear and tear, which reduces the useful life of the system. Furthermore, the presence of the side wall guide posts, the winch, the pulley boxes, and the cables which must cross over the top of the cargo space to connect up to the winch 36 (see FIG. 2) significantly reduces the cargo carrying area of the cargo space for handling piece goods, which results in a decrease in the efficiency of the trailer when used to haul palletized cargo.
There thus exists a need in the art to improve upon and simplify the system for actuating the bulk cargo bags in a bulk cargo convertible freight vehicle.